High soy protein nuggets and applications in food products

ABSTRACT

The present invention relates to food materials containing a high concentration of vegetable protein and processes for their manufacture. More particularly, the present invention relates to vegetable protein extrudates containing high concentrations of protein and low concentrations of carbohydrates, processes for manufacturing such protein extrudates, and the use of such protein extrudates as functional food ingredients.

FIELD OF THE INVENTION

The present invention relates to food materials containing a highconcentration of vegetable protein and processes for their manufacture.More particularly, the present invention relates to vegetable proteinextrudates containing high concentrations of protein and lowconcentrations of carbohydrates, processes for manufacturing suchprotein extrudates, and the use of such protein extrudates as functionalfood ingredients.

BACKGROUND OF THE INVENTION

Texturized vegetable protein products are known in the art and aretypically prepared by heating a mixture of protein material along withwater under mechanical pressure in a cooker extruder and extruding themixture through a die. Upon extrusion, the extrudate generally expandsto form a fibrous cellular structure as it enters a medium of reducedpressure (usually atmospheric). Expansion of the extrudate results frominclusion of soluble carbohydrates which reduce the gel strength of themixture. The extrudates are then used to form other products such asvegetable meat analogs. Extrusion methods for forming textured proteinmeat analogs are well known and disclosed, for example, in U.S. Pat. No.4,099,455.

Extrusion cooking devices have long been used in the manufacture of awide variety of edible and other products such as human and animalfeeds. Generally speaking, these types of extruders include an elongatedbarrel together with one or more internal, helically flighted, axiallyrotatable extrusion screws therein. The outlet of the extruder barrel isequipped with an apertured extrusion die. In use, a material to beprocessed is passed into and through the extruder barrel and issubjected to increasing levels of temperature, pressure and shear. Asthe material emerges from the extruder die, it is fully cooked andshaped and may typically be subdivided using a rotating knife assembly.Conventional extruders of this type are described, for example, in U.S.Pat. Nos. 4,763,569, 4,118,164 and 3,117,006, which are incorporatedherein by reference.

Attempts to develop processes for producing suitable meat substitutesfrom vegetable protein sources include extrusion cooking defatted soyflour or other vegetable proteins in order to texturize and orient thevegetable protein and produce meat extenders in the form of texturizedprotein products for use with hamburger or similar products. Exemplaryprocesses of this type are taught in U.S. Pat. Nos. 3,047,395;3,142,571; 3,488,770 and 3,870,805. Although these extrusion processeshave met with a certain degree of acceptance in the art, the meatsubstitute products heretofore produced have possessed severalcharacteristics which have seriously limited their use, particularly asfull substitutes for meat. One of the most persistent objections tothose prior products stems from the expanded, cellular, spongy naturethereof. In particular, most of these meat extenders are produced underhigh pressure and temperature conditions in the extrusion cooker whichresults in a twisted, randomly oriented meat extender. Afterrehydration, these extenders are characterized by a chewy structure oftwisted layers lacking the appearance, mouth feel or range of utility ofmeat. This has for the most part limited the use of these products tothe role of meat extenders in ground hamburger type meats and the like.Moreover, if too much of the prior vegetable protein product is employedin such hamburger-type meats, the extended meat becomes unacceptablyspongy and exhibits a random, unappealing appearance and mouth feel.

Alternatively, the texturized protein product may be cut into smallerextrudates such as “nuggets” or powders for use as food ingredients oras functional food products.

Regardless of its form, texturized protein products must have anacceptable density, texture, and mouth feel for use as a foodingredient. Thus, conventional texturized protein products typicallyhave a protein content of from about 40% to about 60% by weight on amoisture-free basis. Increasing the protein content of the texturizedproduct has not been feasible because a significant fraction ofcarbohydrate has been deemed necessary to provide the protein extrudatewith an acceptable texture and density. But in certain instances highcarbohydrate functional food ingredients are undesirable to consumerswishing to reduce carbohydrate intake. Thus, a need exists for a highprotein, low carbohydrate texturized protein product having anacceptable density, texture and mouth feel for use as a functional foodingredient.

SUMMARY OF THE INVENTION

Among objects of certain embodiments of the present invention,therefore, may be noted the provision of a novel protein extrudatehaving a high concentration of vegetable protein and a low concentrationof carbohydrates; the provision of such an extrudate having a lowerdensity than conventional protein extrudates containing high levels ofprotein; and the provision of such an extrudate for use as an ingredientor a source of protein in food products.

Briefly, therefore, in one embodiment, the present invention is directedto a protein extrudate comprising at least about 70% by weight vegetableprotein on a moisture-free basis and having a density of from about 0.10g/cm³ to about 0.40 g/cm³.

In another embodiment, the present invention is directed to a proteinextrudate comprising unhydrolyzed vegetable protein and at least about 2parts by weight hydrolyzed protein per part by weight unhydrolyzedprotein.

In another embodiment, the present invention is directed to a functionalfood ingredient comprising from about 40% to about 95% by weight meatmaterial and up to about 4% by weight of a soy protein product on atotal weight basis, the soy protein product comprising at least about70% by weight soy protein on a moisture-free basis and having a densityof from about 0.10 g/cm³ to about 0.40 g/cm³.

In another embodiment, the present invention is directed to a lowdensity snack food product including a majority solids component and awater component with the majority solids component including at leastprotein. The food product comprises protein in the range of betweenabout 25% and about 95% by weight of majority solids component andwater, the protein being derived from seed crops selected from thegroups of cereal grains and legumes; water in the range of between about1% and about 7% by weight of solids and water; and the product ischaracterized by having a crisp texture, a density in the range ofbetween about 0.02 g/cm³ and about 0.5 g/cm³ based on the weight ofsolids component and water.

In another embodiment, the present invention is directed to a lowdensity, low moisture content proteinaceous food product comprising aprincipal solid component and containing between about 1% and about 7%water. The principal solid component comprises protein in aconcentration between about 25% and about 95% by weight of the sum ofthe water content of the product and the dry basis weight of theprincipal solid component, the product being characterized by a crisptexture and a density in the range between about 0.02 g/cm³ and about0.5 g/cm³ based on the weight of said principal solid component andwater.

In another embodiment, the present invention is directed to a lowdensity, low moisture content proteinaceous food product comprising aproteinaceous solid matrix and containing between about 1% and about 7%water. The matrix comprises protein in a concentration between about 25%and about 95% by weight of the sum of the water content of the productand the dry basis weight of said matrix, the product being characterizedby a crisp texture, a density in the range between about 0.02 g/cm³ andabout 0.5 g/cm³.

In another embodiment, the present invention is directed to a lowdensity, low moisture content proteinaceous food product comprising aproteinaceous solid extrudate and containing between about 1% and about7% water. The extrudate comprises protein in a concentration betweenabout 25% and about 95% by weight of the sum of the water content of theproduct and the dry basis weight of said extrudate, the product beingcharacterized by a crisp texture, a density in the range between about0.02 g/cc and about 0.5 g/cc.

In another embodiment, the present invention is directed to a lowdensity, low moisture content proteinaceous food product comprisingbetween about 1% and about 7% water and between about 25% and about 95%by weight of protein, wet basis, the product being characterized by acrisp texture, and a density in the range between about 0.02 g/cm³ andabout 0.5 g/cm³.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic flow sheet of a process useful in preparing theprotein extrudates of the present invention.

FIG. 2 is a photomicrograph of high soy protein textured productsprepared in accordance with the present invention.

FIG. 3 is a photomicrograph of high soy protein textured productsprepared in accordance with the present invention.

FIG. 4 is a photomicrograph of high soy protein textured productsprepared in accordance with the present invention.

FIG. 5 is a photomicrograph of high soy protein textured productsprepared in accordance with the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

In accordance with the present invention, it has been discovered thattextured vegetable protein products containing high concentrations ofprotein and low concentrations of carbohydrates can be manufactured tohave a desired density and an acceptable texture using extrusiontechnology. Such protein extrudates can be formed as “nuggets” orpellets for use as an ingredient or source of protein in health andnutrition bars, snack bars and ready to eat cereal. Alternatively, theprotein extrudates may be further processed for use as a binder, astabilizer or a source of protein in beverages, health and nutritionbars, dairy, and baked and emulsified/ground meat food systems. Incertain embodiments, the protein extrudates may be ground into fineparticles (i.e., powder) to allow for incorporation into soy beverages.Such ground particles typically have a particle size of fromapproximately 1 to about 5 μm to allow suspension in a liquid.

A process of the present invention for preparing protein extrudatesgenerally comprises forming a pre-conditioned feed mixture by contactingthe feed mixture with moisture, introducing the pre-conditioned feedmixture into an extruder barrel, heating the pre-conditioned feedmixture under mechanical pressure to form a molten extrusion mass, andextruding the molten extrusion mass through a die to produce a proteinextrudate.

The protein-containing feed mixture typically comprises at least onesource of protein and has an overall protein concentration of at leastabout 70% protein by weight on a moisture-free basis. Proteins containedin the feed mixture may be obtained from one or more suitable sourcesincluding, for example, dairy protein materials and vegetable proteinmaterials. Dairy protein materials include, for example, casein andsweet dairy whey. Vegetable protein materials may be obtained fromcereal grains such as wheat, corn, and barley, and vegetables such assoybeans and peas. Preferably, the feed mixture contains vegetableproteins and, more preferably, the protein-containing feed mixturecomprises a soy protein material as a source of protein.

Suitable soy protein materials include soy flakes, soy flour, soy grits,soy meal, soy protein concentrates, soy protein isolates, and mixturesthereof. The primary difference between these soy protein materials isthe degree of refinement relative to whole soybeans. Soy flakes aregenerally produced by dehulling, defatting, and grinding the soybean andtypically contain less than about 65 wt. % soy protein on amoisture-free basis. Soy flakes also contain soluble carbohydrates,insoluble carbohydrates such as soy fiber, and fat inherent in soy. Soyflakes may be defatted, for example, by extraction with hexane. Soyflours, soy grits, and soy meals are produced from soy flakes bycomminuting the flakes in grinding and milling equipment such as ahammer mill or an air jet mill to a desired particle size. Thecomminuted materials are typically heat treated with dry heat or steamedwith moist heat to “toast” the ground flakes and inactivateanti-nutritional elements present in soy such as Bowman-Birk and Kunitztrypsin inhibitors. Heat treating the ground flakes in the presence ofsignificant amounts of water is avoided to prevent denaturation of thesoy protein in the material and to avoid costs involved in the additionand removal of water from the soy material. The resulting ground, heattreated material is a soy flour, soy grit, or a soy meal, depending onthe average particle size of the material. Soy flour generally has aparticle size of less than about 150 μm. Soy grits generally have aparticle size of about 150 to about 1000 μm. Soy meal generally has aparticle size of greater than about 1000 μm.

Soy protein concentrates typically contain about 65 wt. % to about 85wt. % soy protein, with the major non-protein component being fiber. Soyprotein concentrates are typically formed from defatted soy flakes bywashing the flakes with either an aqueous alcohol solution or an acidicaqueous solution to remove the soluble carbohydrates from the proteinand fiber. On a commercial scale, considerable costs are incurred withthe handling and disposing of the resulting waste stream.

Soy protein isolates, more highly refined soy protein materials, areprocessed to contain at least 90% soy protein and little or no solublecarbohydrates or fiber. Soy protein isolates are typically formed byextracting soy protein and water soluble carbohydrates from defatted soyflakes or soy flour with an alkaline aqueous extractant. The aqueousextract, along with the soluble protein and soluble carbohydrates, isseparated from materials that are insoluble in the extract, mainlyfiber. The extract is typically then treated with an acid to adjust thepH of the extract to the isoelectric point of the protein to precipitatethe protein from the extract. The precipitated protein is separated fromthe extract, which retains the soluble carbohydrates, and is dried afterbeing adjusted to a neutral pH or is dried without any pH adjustment. Ona commercial scale, these steps contribute significant cost to theproduct.

In preparation of the high protein extrudates, a feed mixture comprisingat least about 70 wt. % protein, on a moisture-free basis (i.e., drybasis), is prepared. More preferably, the feed mixture comprises atleast about 80% by weight protein on a moisture-free basis and, stillmore preferably, the feed mixture comprises at least about 90% by weightvegetable protein on a moisture-free basis.

The overall protein content of the feed mixture may be achieved by acombination (i.e., blend) of suitable sources of protein describedabove.

In certain embodiments, it is preferred for soy protein isolates toconstitute one or more of the sources of protein contained in the feedmixture. This is generally due to the higher degree of refinement of soyprotein isolates as compared to the other soy protein materialsdescribed above and, in particular, due to soy protein isolatescontaining the highest protein content and lowest carbohydrate contentof the soy protein materials. For example, a preferred feed mixtureformulation may comprise a blend of two or more soy protein isolates.Other suitable formulations may comprise a soy protein concentrate incombination with a soy protein isolate. Typically, a protein-containingfeed mixture comprising one or more soy protein isolates contains fromabout 75% to about 100% by weight soy protein isolate on a moisture-freebasis and, accordingly, from about 70% to about 95% by weight protein.

Generally, the bulk density of the source of soy protein or blend ofsources is from about 0.20 g/cm³ to about 0.50 g/cm³ and, moretypically, from about 0.24 g/cm³ to about 0.44 g/cm³.

In certain embodiments in which the feed mixture comprises a pluralityof soy protein materials, it is desired that at least one of the soyprotein materials exhibits low viscosity and low gelling properties. Theviscosity and/or gelling properties of an isolated soy protein may bemodified by a wide variety of methods known in the art. For example, theviscosity and/or gelling properties of a soy protein isolate may bedecreased by partial hydrolysis which partially denatures the proteinmaterials. Typically, soy protein materials treated in this manner aredescribed in terms of degree of hydrolysis which can be determined basedon molecular weight distributions, sizes of proteins and chain lengths,or breaking down of beta-conglycinin or glycinin storage proteins. Asused herein, the term “percent degree of hydrolysis” of a sample isdefined as the percentage of cleaved peptide bonds out of the totalnumber of peptide bonds in the sample. The proportion of cleaved peptidebonds in a sample can be measured by calculating the amount oftrinitrobenzene sulfonic acid (TNBS) that reacts with primary amines inthe sample under controlled conditions.

Trinitrobenzene sulfonic acid (TNBS) reacts under controlled conditionswith the primary amines of proteins to produce a chromophore whichabsorbs light at 420 nm. The intensity of color produced from theTNBS-amine reaction is proportional to the total number of aminoterminal groups and therefore is an indicator of the degree ofhydrolysis of a sample. In conducting the TNBS assay, 0.2 ml of 0.3 MTNBS solution is reacted with 2 ml of a protein sample prepared byslurrying 0.1 grams of protein material in 100 ml of 0.0245 N NaOH. Thereaction is carried out in the presence of a 9.5 pH sodium boratebuffer. The reaction is allowed to proceed for 15 minutes after whichtime the reaction is terminated and the absorbance of the reactionsolution and the protein sample are measured. The absorbance valuesprovide the TNBS value which represents the moles of free amino acidsproduced per 100 kg of protein which is calculated according to thefollowing formula: TNBS value=(As₄₂₀−Ab₄₂₀)×(8.073)×(1/W)×F×100/P. As₄₂₀is the TNBS absorbance of the sample. Ab₄₂₀ is the TNBS absorbance ofthe reaction solution. W is the weight of sample. F is the inverse ofdilution factor of the measured sample to the sample produced by thereaction (i.e., diluting the reaction sample by a factor of 10 beforemeasuring its absorbance provides a dilution factor of 0.1). 8.073 isthe extinction coefficient and dilution factor/unit conversion for theprocedure. P is the protein content of the sample determined using theKjeldahl method described below. Such measurement procedures aredescribed, for example, by Adler-Nissen in J. Agric. Food Chem., Vol.27(6), p. 1256 (1979).

Percent degree of hydrolysis is determined from the TNBS value using thefollowing equation: % degree of hydrolysis=((TNBS_(value)−24)/885)×100.24 is the correction for lysyl amino group of a non-hydrolyzed sampleand 885 is the moles of amino acid per 100 kg of protein.

The Nitrogen-Ammonia-Protein Modified Kjeldahl Method of A.O.C.S.Methods Bc4-91 (1997), Aa 5-91 (1997), and Ba 4d-90(1997) used in thedetermination of the protein content may be performed as follows with asoy material sample. 0.0250-1.750 grams of the soy material are weighedinto a standard Kjeldahl flask. A commercially available catalystmixture of 16.7 grams potassium sulfate, 0.6 grams titanium dioxide,0.01 grams of copper sulfate, and 0.3 grams of pumice is added to theflask, then 30 milliliters of concentrated sulfuric acid is added to theflask. Boiling stones are added to the mixture, and the sample isdigested by heating the sample in a boiling water bath for approximately45 minutes. The flask should be rotated at least 3 times during thedigestion. 300 milliliters of water is added to the sample, and thesample is cooled to room temperature. Standardized 0.5N hydrochloricacid and distilled water are added to a distillate receiving flasksufficient to cover the end of a distillation outlet tube at the bottomof the receiving flask. Sodium hydroxide solution is added to thedigestion flask in an amount sufficient to make the digestion solutionstrongly alkaline. The digestion flask is then immediately connected tothe distillation outlet tube, the contents of the digestion flask arethoroughly mixed by shaking, and heat is applied to the digestion flaskat about a 7.5-min boil rate until at least 150 milliliters ofdistillate is collected. The contents of the receiving flask are thentitrated with 0.25N sodium hydroxide solution using 3 or 4 drops ofmethyl red indicator solution—0.1% in ethyl alcohol. A blankdetermination of all the reagents is conducted simultaneously with thesample and similar in all respects, and correction is made for blankdetermined on the reagents. The moisture content of the ground sample isdetermined according to the procedure described below (A.O.C.S OfficialMethod Ba 2a-38). The nitrogen content of the sample is determinedaccording to the formula: Nitrogen (%)=1400.67×[[(Normality of standardacid)×(Volume of standard acid used for sample (ml))]−[(Volume ofstandard base needed to titrate 1 ml of standard acid minus volume ofstandard base needed to titrate reagent blank carried through method anddistilled into 1 ml standard acid (ml))×(Normality of standardbase)]−[(Volume of standard base used for the sample (ml))×(Normality ofstandard base)]]/(Milligrams of sample). The protein content is 6.25times the nitrogen content of the sample.

The term “moisture content” as used herein refers to the amount ofmoisture in a material. The moisture content of a soy material can bedetermined by A.O.C.S. (American Oil Chemists Society) Method Ba 2a-38(1997), which is incorporated herein by reference in its entirety.According to the method, the moisture content of a soy material may bemeasured by passing a 1000 gram sample of the soy material through a 6×6riffle divider, available from Seedboro Equipment Co., Chicago, Ill.,and reducing the sample size to 100 grams. The 100 gram sample is thenimmediately placed in an airtight container and weighed. 5 grams of thesample are weighed onto a tared moisture dish (minimum 30 gauge,approximately 50×20 millimeters, with a tight-fitting slipcover—available from Sargent-Welch Co.). The dish containing the sampleis placed in a forced draft oven and dried at 130+/−3° C. for 2 hours.The dish is then removed from the oven, covered immediately, and cooledin a dessicator to room temperature. The dish is then weighed. Moisturecontent is calculated according to the formula: Moisture content(%)=100×[(loss in mass (grams)/mass of sample (grams)].

Hydrolyzed protein materials used in accordance with the process of thepresent invention typically exhibit TNBS values of less than about 160,more typically less than about 115 and, still more typically, from about30 to about 70.

Hydrolyzed soy protein sources sufficient for use as a low viscosity/lowgelling material in the process of the present invention typically havea degree of hydrolysis of less than about 15%, more typically less thanabout 10% and, still more typically, from about 1% to about 5%. In thecase of soy protein isolates, the hydrolyzed soy protein materialtypically comprises a partially hydrolyzed isolate having a degree ofhydrolysis of from about 1% to about 5%.

Suitable methods for hydrolysis of soy protein sources include acidhydrolysis and caustic hydrolysis. Soy protein sources (e.g., a soyprotein isolate) may also be hydrolyzed by treatment of the materialwith an enzyme such as a protease obtained from a plant or microbialsource; for example, contacting the isolate with a protease at a pH offrom about 7 to about 8. Suitable proteolytic enzymes include bromelinand papain. It is currently believed that proteolytic hydrolysis attackscertain peptide bonds, thereby reducing the molecular weights of certainproteins present in the proteins in the feed mixture.

The viscosity and/or gelling properties of dairy whey may also bemodified by partial hydrolysis. Hydrolysis may be carried out by, forexample, treating the dairy whey with a proteolytic enzyme. Suitableproteolytic enzymes include, for example, bromelin, papain, and rennin.

Gel strength, expressed in terms of the extent of gelation (G) may bedetermined by preparing a slurry (commonly 200 grams of a slurry havinga 1:5 weight ratio of soy protein source to water) to be placed in aninverted frustoconical container which is placed on its side todetermine the amount of the slurry that flows from the container. Thecontainer has a capacity of approximately 150 ml (5 ounces), height of 7cm, top inner diameter of 6 cm, and a bottom inner diameter of 4 cm. Theslurry sample of the soy protein source may be formed by cutting orchopping the soy protein source with water in a suitable food cutterincluding, for example, a Hobart Food Cutter manufactured by HobartCorporation (Troy, Ohio). The extent of gelation, G, indicates theamount of slurry remaining in the container over a set period of time.Low viscosity/low gelling sources of soy protein suitable for use inaccordance with the present invention typically exhibit an extent ofgelation, on a basis of 200 grams of sample introduced to the containerand taken five minutes after the container is placed on its side, offrom about 1 to about 80 grams (i.e., from about 1 to about 80 grams,0.5% to about 40%, of the slurry remains in the container five minutesafter the container is placed on its side). High viscosity/medium tohigh gelling sources of soy protein suitable for use in accordance withthe present invention typically exhibit an extent of gelation, on thesame basis described above, of from about 45 to about 140 grams (i.e.,from about 45 to about 140 grams, 22% to about 70%, of the slurryremains in the container five minutes after the container is placed onits side). A blend of sources comprising a low viscosity/low gellingsource and a high viscosity/high gelling source typically have agelation rate, on the same basis, of from about 20 to about 120 grams.

In accordance with the present invention, a low viscosity/low gellingsource is preferably combined with a high viscosity/high gelling sourceto form the blend. The presence of the high viscosity/high gellingsource reduces the risk of excessive expansion of the blend uponextrusion, provides a honeycomb structure to the extrudate, andgenerally contributes stability to the blend. The low viscosity/lowgelling and high viscosity/high gelling sources can be combined invarying proportions depending on the desired characteristics of theextrudate.

In a preferred embodiment, the protein-containing feed mixture typicallycomprises a blend of soy protein isolates comprising at least about 2parts by weight of a hydrolyzed (i.e., generally low viscosity/lowgelling) protein isolate per part by weight of an unhydrolyzed (i.e.,generally high viscosity/high gelling) protein isolate, more typicallyat least about 3 parts by weight of a hydrolyzed protein isolate perpart by weight of an unhydrolyzed protein isolate and, still moretypically, at least about 4 parts by weight of a hydrolyzed proteinisolate per part by weight of an unhydrolyzed protein isolate.Preferably, the blend of soy protein isolates comprises from about 2parts by weight to about 8 parts by weight of a hydrolyzed proteinisolate per part by weight of an unhydrolyzed protein isolate. Morepreferably, the blend of soy protein isolates comprises from about 4parts by weight to about 6 parts by weight of a hydrolyzed proteinisolate per part by weight of an unhydrolyzed protein isolate.

Blends comprising a plurality of soy protein isolates, one of which is alow viscosity/low gelling source produced by partial hydrolysis of a soyprotein isolate typically comprise from about 60% to about 100% byweight of a hydrolyzed protein isolate on a moisture-free basis and fromabout 0% to about 33% by weight of an unhydrolyzed protein isolate on amoisture-free basis. More typically, such blends comprise from about 60%to about 90% by weight of a hydrolyzed protein isolate on amoisture-free basis and from about 0% to about 20% by weight of anunhydrolyzed isolate on a moisture-free basis. More typically, suchblends comprise from about 60% to about 90% by weight of a hydrolyzedprotein isolate on a moisture-free basis and from about 5% to about 20%by weight of an unhydrolyzed isolate on a moisture-free basis. Stillmore typically, such blends comprise from about 65% to about 85% byweight of a hydrolyzed protein isolate on a moisture-free basis and fromabout 10% to about 20% by weight of an unhydrolyzed isolate on amoisture-free basis. Even more typically, such blends comprise fromabout 65% to about 75% by weight of a hydrolyzed protein isolate on amoisture-free basis and from about 15% to about 20% by weight of anunhydrolyzed isolate on a moisture-free basis. With respect to certainprotein sources (e.g., casein) higher ratios of unhydrolyzed tohydrolyzed protein are acceptable, up to and including 100% casein.

Suitable isolated soy protein sources exhibiting a low viscosity and/orlow gelling (i.e., partially hydrolyzed) for use as a low viscosity/lowgelling soy protein material include SUPRO 670 and SUPRO 710, availablefrom The Solae Company (St. Louis, Mo.), and PROFAM 931 and PROFAM 873available from Archer Daniels Midland (Decatur, Ill.). For both SUPRO670 and SUPRO 710, the degree of hydrolysis can range from 0.5%-5.0%.The molecular weight distribution of each of these isolates can bedetermined by size exclusion chromatography.

Suitable sources of high viscosity and/or medium/high gelling isolatedsoy protein (i.e., unhydrolyzed) for use as the second soy proteinisolate include SUPRO 620, SUPRO 500E, SUPRO 630, and SUPRO EX33available from The Solae Company (St. Louis, Mo.); PROFAM 981 availablefrom Archer Daniels Midland (Decatur, Ill.); and PROLISSE soy proteinisolate available from Cargill Soy Protein Solutions, Inc. (Minneapolis,Minn.).

Table 1 provides molecular weight distributions for certain of thecommercial SUPRO® products mentioned above. TABLE 1 Estimated MolecularWeight Distribution of SUPRO ® products determined at an absorbance of280 nm using HPLC- SEC (High Performance Liquid Chromatography - SizeExclusion Chromatography) gel filtration in 6M guanidine HCl.Product >50,000 20,000-50,000 5000-20,000 2000-5000 SUPRO ® 620 21%  44%30%  5% SUPRO ® 670 7% 17% 55% 21% SUPRO ® 710 2% 12% 55% 31%

The protein-containing feed mixture may also contain one or more solublecarbohydrate sources in an amount of from about 0.001% to about 20% byweight soluble carbohydrates on a moisture-free basis. Typically, theprotein-containing feed mixture comprises from about 0% to about 10% byweight soluble carbohydrates on a moisture-free basis. Suitable sourcesof soluble carbohydrates include, for example, cereals, tubers and rootssuch as rice (e.g., rice flour), wheat, corn, barley, potatoes (e.g.,native potato starch), and tapioca (e.g., native tapioca starch).

In addition to soluble carbohydrates, the feed mixture may also containinsoluble carbohydrate such as soy fiber which does not contribute tonutritive carbohydrate load and which, generally, is present as an aidin processing of the mixture because the fiber serves to facilitateflowability and expansion of the feed mixture. When soy fiber is presentin the mixture to serve either as filler to increase the volume of themixture or as a processing aid, the amount of fiber present can varywidely. Generally, however, the feed mixture comprises from about 0.001%to about 5% by weight fiber and, more generally, from about 1% to about3% by weight fiber. Soy fiber absorbs moisture as the extrusion massflows through the extrusion barrel to the die. A modest concentration ofsoy fiber is believed to be effective in obstructing cross-linking ofprotein molecules, thus preventing excessive gel strength fromdeveloping in the cooked extrusion mass exiting the die. Unlike theprotein, which also absorbs moisture, soy fiber readily releasesmoisture upon release of pressure at the die exit temperature. Flashingof the moisture released contributes to expansion, i.e., “puffing,” ofthe extrudate, thus conducing to the formation of the low densityextrudate of the invention.

Referring now to FIG. 1, one embodiment of the process of the presentinvention is shown. The process comprises introducing the particularingredients of the protein-containing feed mixture formulation into amixing tank 101 (i.e., an ingredient blender) to combine the ingredientsand form a protein feed pre-mix. The pre-mix is then transferred to ahopper 103 where the pre-mix is held for feeding via screw feeder 105 toa pre-conditioner 107 to form a conditioned feed mixture. Theconditioned feed mixture is then fed to an extrusion apparatus (i.e.,extruder) 109 in which the feed mixture is heated under mechanicalpressure generated by the screws of the extruder to form a moltenextrusion mass. The molten extrusion mass exits the extruder through anextrusion die.

In pre-conditioner 107, the particulate solid ingredient mix ispreheated, contacted with moisture, and held under controlledtemperature and pressure conditions to allow the moisture to penetrateand soften the individual particles. The preconditioning step increasesthe bulk density of the particulate feed mixture and improves its flowcharacteristics. The preconditioner 107 contains one or more paddles topromote uniform mixing of the feed and transfer of the feed mixturethrough the preconditioner. The configuration and rotational speed ofthe paddles vary widely, depending on the capacity of thepreconditioner, the extruder throughput and/or the desired residencetime of the feed mixture in the preconditioner or extruder barrel.Generally, the speed of the paddles is from about 500 to about 1300revolutions per minute (rpm).

Typically, the protein-containing feed mixture is pre-conditioned priorto introduction into the extrusion apparatus 109 by contacting a pre-mixwith moisture (i.e., steam and/or water) at a temperature of at leastabout 45° C. (110° F.). More typically, the feed mixture is conditionedprior to heating by contacting a pre-mix with moisture at a temperatureof from about 45° C. (110° F.) to about 85° C. (185° F.). Still moretypically, the feed mixture is conditioned prior to heating bycontacting a pre-mix with moisture at a temperature of from about 45° C.(110° F.) to about 70° C. (160° F.). It has been observed that highertemperatures in the preconditioner may encourage starches to gelatinize,which in turn may cause lumps to form which may impede flow of the feedmixture from the preconditioner to the extruder barrel.

Typically, the pre-mix is conditioned for a period of about 30 to about60 seconds, depending on the speed and the size of the conditioner. Moretypically, the pre-mix is conditioned for a period of from about 40 toabout 50 seconds, most typically about 45 seconds. The pre-mix iscontacted with steam and/or water and heated in the pre-conditioner 107at generally constant steam flow to achieve the desired temperatures.The water and/or steam conditions (i.e., hydrates) the feed mixture,increases its density, and facilitates the flowability of the dried mixwithout interference prior to introduction to the extruder barrel wherethe proteins are texturized. In certain embodiments, the feed mixturepre-mix is contacted with both water and steam to produce a conditionedfeed mixture. For example, experience to date suggests that it may bepreferable to add both water and steam to increase the density of thedry mix as steam contains moisture to hydrate the dry mix and alsoprovides heat which promotes hydration of the dry mix by the water.

The conditioned pre-mix may contain from about 5% to about 25% by weightwater. Preferably, the conditioned pre-mix contains from about 5% toabout 15% by weight water. The conditioned pre-mix typically has a bulkdensity of from about 0.25 g/cm³ to about 0.6 g/cm³. Generally, as thebulk density of the pre-conditioned feed mixture increases within thisrange, the feed mixture is easier to process. This is presently believedto be due to such mixtures occupying all or a majority of the spacebetween the screws of the extruder, thereby facilitating conveying theextrusion mass through the barrel.

The conditioned pre-mix is generally introduced to the extrusionapparatus 109 at a rate of no more than about 10 kilograms (kg)/min (nomore than about 20 lbs/min). Typically, the conditioned pre-mix isintroduced to the barrel at a rate of from about 2 to about 10 kg/min(from about 5 to about 20 lbs/min), more typically from about 5 to about10 kg/min (from about 10 to about 20 lbs/min) and, still more typically,from about 6 to about 8 kg/min (from about 12 to about 18 lbs/min).Generally, it has been observed that the density of the extrudatedecreases as the feed rate of pre-mix to the extruder increases. Theresidence time of the extrusion mass in the extruder barrel is typicallyless than about 60 seconds, more typically less than about 30 secondsand, still more typically, from about 15 to about 30 seconds.

Typically, extrusion mass passes through the barrel at a rate of fromabout 7.5 kg/min to about 40 kg/min (from about 17 lbs/min to about 85lbs/min). More typically, extrusion mass passes through the barrel at arate of from about 7.5 kg/min to about 30 kg/min (from about 17 lbs/min65 lbs/min). Still more typically, extrusion mass passes through thebarrel at a rate of from about 7.5 kg/min to about 22 kg/min (from about17 lbs/min to about 50 lbs/min). Even more typically, extrusion masspasses through the barrel at a rate of 7.5 kg/min to about 15 kg/min(from about 17 lbs/min to about 35 lbs/min).

Various extrusion apparatus suitable for forming a molten extrusion massfrom a feed material comprising vegetable protein are well known in theart. One suitable extrusion apparatus is a double-barrel, twin screwextruder as described, for example, in U.S. Pat. No. 4,600,311. Examplesof commercially available double-barrel, twin screw extrusion apparatusinclude a CLEXTRAL Model BC-72 extruder manufactured by Clextral, Inc.(Tampa, Fla.) having an L/D ratio of 13.5:1 and four heating zones; aWENGER Model TX-57 extruder manufactured by Wenger (Sabetha, Kans.)having an L/D ratio of 14:1 and four heating zones; and a WENGER ModelTX-52 extruder manufactured by Wenger (Sabetha, Kans.) having an L/Dratio of 14:1 and four heating zones. Other suitable extruders includeCLEXTRAL Models BC-82 and BC-92 and WENGER Models TX-138, TX-144,TX-162, and TX-168.

The ratio of the length and diameter of the extruder (L/D ratio)generally determines the length of extruder necessary to process themixture and affects the residence time of the mixture therein. Generallythe L/D ratio is greater than about 10:1, greater than about 15:1,greater than about 20:1, or even greater than about 25:1.

The screws of a twin screw extruder can rotate within the barrel in thesame or opposite directions. Rotation of the screws in the samedirection is referred to as single flow whereas rotation of the screwsin opposite directions is referred to as double flow.

The speed of the screw or screws of the extruder may vary depending onthe particular apparatus. However, the screw speed is typically fromabout 250 to about 350 revolutions per minute (rpm), more typically fromabout 250 to about 335 rpm and, still more typically, from about 270 toabout 305 rpm. Generally, as the screw speed increases, the density ofthe extrudates decreases.

The extrusion apparatus 109 generally comprises a plurality of heatingzones through which feed mixture is conveyed under mechanical pressureprior to exiting the extrusion apparatus 109 through an extrusion die.The temperature in each successive heating zone generally exceeds thetemperature of the previous heating zone by between about 10 C° andabout 70 C° (between about 15 F° and about 125 F°), more generally bybetween about 10 C° and about 50 C° (from about 15 F° to about 90 F°)and, more generally, from about 10 C° to about 30 C° (from about 15 F°to about 55 F°).

Typically, the temperature in the last heating zone is from about 90° toabout 150° C. (from about 195° to about 300° F.), more typically fromabout 100° to about 150° C. (from about 212° to about 300° F.) and,still more typically, from about 100° to about 130° C. (from about 210°to about 270° F.)

Typically, the temperature in the next to last heating zone is fromabout 80° to about 120° C. (from about 175° to about 250° F.) and, moretypically, from about 90° to about 110° C. (from about 195° to about230° F.).

Typically, the temperature in the heating zone immediately before thenext to last heating zone is from about 70° to about 100° C. (from about160° to about 210° F.) and, more typically, from about 80° to about 90°C. (from about 175° to about 195° F.).

Typically, the temperature in the heating zone separated from the lastheating zone by two heating zones is from about 60° to about 90° C.(from about 140° to about 195° F.) and, more typically, from about 70°to about 80° C. (from about 160° to about 175° F.).

Typically, the extrusion apparatus comprises at least about threeheating zones and, more typically, at least about four heating zones. Ina preferred embodiment, the conditioned pre-mix is transferred throughfour heating zones within the extrusion apparatus, with the feed mixtureheated to a temperature of from about 100° to about 150° C. (from about212° to about 302° F.) such that the molten extrusion mass enters theextrusion die at a temperature of from about 100° to about 150° C. (fromabout 212° to about 302° F.)

In such an embodiment, the first heating zone is preferably operated ata temperature of from about 60° to about 90° C. (from about 140° toabout 195° F.), the second heating zone is operated at a temperature offrom about 70° to about 100° C. (from about 160° to about 212° F.), thethird heating zone is operated at a temperature of from about 80° toabout 120° C. (from about 175° to about 250° F.) and the fourth heatingzone is operated at a temperature of from about 90° to about 150° C.(from about 195° to about 302° F.).

The temperature within the heating zones may be controlled usingsuitable temperature control systems including, for example, Mokontemperature control systems manufactured by Clextral (Tampa, Fla.).Steam may also be introduced to one or more heating zones via one ormore valves in communication with the zones to control the temperature.

Apparatus used to control the temperature of the heating zones may beautomatically controlled. One such control system includes suitablevalves (e.g., solenoid valves) in communication with a programmablelogic controller (PLC).

The pressure within the extruder barrel is not narrowly critical.Typically the extrusion mass is subjected to a pressure of at leastabout 400 psig (about 28 bar) and generally the pressure within the lasttwo heating zones is from about 1000 psig to about 3000 psig (from about70 bar to about 210 bar). The barrel pressure is dependent on numerousfactors including, for example, the extruder screw speed, feed rate ofthe mixture to the barrel, feed rate of water to the barrel, and theviscosity of the molten mass within the barrel.

The heating zones within the barrel may be characterized in terms of theaction upon the mixture therein. For example, zones in which the primarypurpose is to convey the mixture longitudinally along the barrel aregenerally referred to as “conveying zones” and zones in which theprimary purpose is mixing are generally referred to as “mixing zones.”Zones in which the primary purpose is to compress the mixture aregenerally referred to as “compression zones” and zones in which theprimary purpose is to provide shearing of the proteins are referred toas “shearing zones.” It should be understood that more than one actionmay occur within a zone; for example, there may be“shearing/compression” zones or “mixing/shearing” zones. The action uponthe mixture within the various zones is generally determined by variousconditions within the zone including, for example, the temperature ofthe zone and the screw profile within the zone.

The extruder is characterized by its screw profile which is determined,at least in part, by the length to pitch ratio of the various portionsof the screw. Length (L) indicates the length of the screw while pitch(P) indicates the distance required for 1 full rotation of a thread ofthe screw. In the case of a modular screw containing a plurality ofscrew portions having varying characteristics, L can indicate the lengthof such a portion and P the distance required for 1 full rotation of athread of the screw. The intensity of mixing, compression, and/orshearing generally increases as the pitch decreases and, accordingly,L:P increases. L:P ratios for the twin-screws within the various heatingzones of one embodiment of the present invention are provided below inTable 2. TABLE 2 Zone L:P Flow Conveying 200/100 Double flow Conveying200/100 Double flow Conveying 150/100 Double flow Compression 200/66Double flow Compression 200/66 Double flow Shearing 100/50 Double flowShearing 100/40 Single flow Shearing 100/30 Single flow (reverse)

Water is injected into the extruder barrel to hydrate the feed mixtureand promote texturization of the proteins. As an aid in forming themolten extrusion mass the water may act as a plasticizing agent. Watermay be introduced to the extruder barrel via one or more injection jetsin communication with a heating zone. Typically, the mixture in thebarrel contains from about 15% to about 30% by weight water. The rate ofintroduction of water to any of the heating zones is generallycontrolled to promote production of an extrudate having desiredcharacteristics. It has been observed that as the rate of introductionof water to the barrel decreases, the density of the extrudatedecreases. Typically, less than about 1 kg of water per kg of proteinare introduced to the barrel and, more typically less than about 0.5 kgof water per kg of protein and, still more typically, less than about0.25 kg of water per kg of protein are introduced to the barrel.Generally, from about 0.1 kg to about 1 kg of water per kg of proteinare introduced to the barrel.

Referring again to FIG. 1, the molten extrusion mass in extrusionapparatus 109 is extruded through a die (not shown) to produce anextrudate, which is then dried in dryer 111.

Extrusion conditions are generally such that the product emerging fromthe extruder barrel typically has a moisture content of from about 20%to about 45% by weight wet basis and, more typically, from about 30% toabout 40% by weight wet basis. The moisture content is derived fromwater present in the mixture introduced to the extruder, moisture addedduring preconditioning and/or any water injected into the extruderbarrel during processing.

Upon release of pressure, the molten extrusion mass exits the extruderbarrel through the die, superheated water present in the mass flashesoff as steam, causing simultaneous expansion (i.e., puffing) of thematerial. The level of expansion of the extrudate upon exiting ofmixture from the extruder in terms of the ratio of the cross-sectionalarea of extrudate to the cross-sectional area of die openings isgenerally less than about 15:1, more generally less than about 10:1 and,still more generally, less than about 5:1. Typically, the ratio of thecross-sectional area of extrudate to the cross-sectional area of dieopenings is from about 2:1 to about 11:1 and, more typically, from about2:1 to about 10:1.

The extrudate is cut after exiting the die. Suitable apparatus forcutting the extrudate include flexible knives manufactured by Wenger(Sabetha, Kans.) and Clextral (Tampa, Fla.).

The dryer 111 used to dry the extrudates generally comprises a pluralityof drying zones in which the air temperature may vary. Generally, thetemperature of the air within one or more of the zones will be fromabout 135° to about 185° C. (from about 280° to about 370° F.).Typically, the temperature of the air within one or more of the zones isfrom about 140° to about 180° C. (from about 290° to about 360° F.),more typically from about 155° to 170° C. (from about 310° to 340° F.)and, still more typically, from about 160° to about 165° C. (from about320° to about 330° F.). Typically, the extrudate is present in the dryerfor a time sufficient to provide an extrudate having a desired moisturecontent. This desired moisture content may vary widely depending on theintended application of the extrudate and, typically, is from about 2.5%to about 5.0% by weight. Generally, the extrudate is dried for at leastabout 5 minutes and, more generally, for at least about 10 minutes.Suitable dryers include those manufactured by Wolverine Proctor &Schwartz (Merrimac, Mass.), National Drying Machinery Co. (Philadelphia,Pa.), Wenger (Sabetha, KS), Clextral (Tampa, Fla.), and Buehler (LakeBluff, Ill.).

The extrudates may further be comminuted to reduce the average particlesize of the extrudate. Suitable grinding apparatus include hammer millssuch as Mikro Hammer Mills manufactured by Hosokawa Micron Ltd.(England).

Preferably, the novel protein extrudates of the present inventioncomprise at least about 70% by weight protein on a moisture-free basis,more preferably at least about 80% by weight protein on a moisture-freebasis and, still more preferably, at least about 90% by weight proteinon a moisture-free basis. In one preferred embodiment, the proteinextrudate comprises from about 80% to about 95% by weight protein on amoisture-free basis.

The protein extrudates comprise vegetable protein and may also includeother components including fiber (e.g., soy fiber and cereal fiber),carbohydrates (e.g., complex carbohydrates such as starches), and water.Preferably, a majority of the protein in the food product comprises soyproteins and, preferably, the source of a majority of the protein in theextrudate is one or more soy protein isolates.

In one embodiment, the protein extrudate is in the form of a low densitysnack product including a majority solids component and a watercomponent. Typically, such products include between about 25% and about95% protein on a majority solids component and water component basis.

In another embodiment, the protein extrudate is in the form a lowdensity, low moisture content proteinaceous food product comprising aprincipal solid component which includes protein in a concentration ofbetween about 25% and about 95% by weight of the water present in theproduct and the dry basis weight of the principal solid component. Inone variation of this embodiment, the principal solid component is inform of a proteinaceous solid matrix and, in another, a proteinaceoussolid extrudate.

Generally, the protein extrudates of the present invention generallyhave a density of from about 0.1 g/cm³ to about 0.4 g/cm³. Preferably,the protein extrudates of the present invention have a density of fromabout 0.15 g/cm³ to about 0.35 g/cm³. In such embodiments, the densityof the extrudate may be from about 0.20 g/cm³ to about 0.27 g/cm³, fromabout 0.24 g/cm³ to about 0.27 g/cm³, or from about 0.27 g/cm³ to about0.32 g/cm³.

Low density snack food products prepared in accordance with the presentinvention generally have a density of from about 0.02 g/cm³ to about 0.7g/cm³ and, more generally, from about 0.02 g/cm³ to about 0.5 g/cm³.Generally, such extrudates exhibit a crisp, non-fibrous eating texture.In certain embodiments, the products have a density of from about 0.02g/cm³ to about 0.1 g/cm³ or even from about 0.02 g/cm³ to about 0.05g/cm³. Low density, low moisture content proteinaceous food productscomprising a principal solid component typically exhibit such densities.

In a preferred embodiment, the protein extrudates of the presentinvention comprise hydrolyzed soy protein and unhydrolyzed soy proteinas described above. Typically, the protein extrudate comprises at leastabout 1 part by weight hydrolyzed soy protein per part by weightunhydrolyzed soy protein and, more preferably at least 2 parts by weighthydrolyzed soy protein per part by weight unhydrolyzed soy protein.

More typically, the protein extrudate comprises from about 2 to about 8parts by weight hydrolyzed soy protein per part by weight unhydrolyzedsoy protein, from about 2 to about 4 parts by weight hydrolyzed soyprotein per part by weight unhydrolyzed soy protein, or from about 4 toabout 6 parts by weight hydrolyzed soy protein per part by weightunhydrolyzed soy protein.

In certain embodiments, the food product includes hydrolyzed soy proteinand at least partially hydrolyzed soy protein isolates and unhydrolyzedsoy protein (e.g., a soy protein isolate, a soy protein concentrate, orsoy flour) and the partially hydrolyzed protein is present in theproduct in a weight ratio of between 80:20 to 55:45 to the unhydrolyzedsoy protein.

Preferably, the extrudate contains less than about 20% by weightcarbohydrates, more preferably less than about 10% by weightcarbohydrates, still more preferably less than about 5% by weight and,even more preferably, from about 2% to about 5% by weight carbohydrates.

Carbohydrate (i.e., starch) present in the feed mixture typically formsmicroparticles of starch gels under the conditions of the extruderbarrel caused by denaturing of starches. Thus, the starch present ispartially gelatinized. The degree of starch gelatinization of the starchportions of the extrudate may be determined by a starch iodine test orby polarized microscopy. Typically, the starch present in the extrudateexhibits a degree of gelatinization of from about 70% to about 90%.While the starch is not present in an amount sufficient to provide agelatinous character to the extrudate, its degree of gelatinization canbe used as a measure of the degree of “cooking” of the extrusion masswithin the barrel as generally increased temperatures are necessary forgelatinization of starches.

Typically, the extrudates contains from about 0.001% to about 5% byweight fiber on a moisture free basis and, more typically, from about 1%to about 3% by weight fiber on a moisture free basis. Fiber in theextrusion mass aids in expansion of the extrusion mass as it exits theextrusion die. It is presently believed that fiber in the extrusion massdisrupts formation of bonds between proteins which generally form amatrix which tends to trap water present in the mixture and preventexpansion. This disruption of bond formation and the natural tendency ofthe fiber to release water facilitates flashing of water from theextrusion mass as steam and expansion of the extrusion mass.

In addition to protein, the majority solids component or principal solidcomponent of food products of the present invention may comprise othersolid components (i.e., fillers) such as carbohydrates or fibers. Theproduct may include filler in a ratio of filler to protein in the rangeof from about 5:95 to about 75:25. In certain embodiments, a majority ofthe filler is starch. Suitable starches include rice flour, potato,tapioca, and mixtures thereof.

Generally, water is present in the dried extrudate at a concentration offrom about 2% to about 5.5% by weight. The amount of water may varydepending on other characteristics of the extrudate (e.g., carbohydratecontent and density).

Low density food products of the present invention including a majoritysolids component or a principal solid component typically contain waterat a concentration of between about 1% and about 7% by weight ofprotein, filler, and water and, more typically, between about 3% andabout 5% by weight of protein, filler, and water.

The protein extrudates of the present invention may further becharacterized as having a hardness of at least about 1000 grams.Typically, the protein extrudates have a hardness of from about 1000 toabout 50,000 grams and, more typically, from about 30,000 to about45,000 grams. The hardness of the extrudates is generally determined byplacing an extrudate sample in a container and crushing the sample witha probe. The force required to break the sample is recorded; the forcethat is required to crush the sample based on its size or weight isproportional to the hardness of the product. The hardness of theextrudates may be determined using a TA.TXT2 Texture Analyzer having a25 kg load cell, manufactured by Stable Micro Systems Ltd. (England).Extrudates having a chewy texture are preferred in certain embodiments.Generally, such extrudates have a hardness of less than about 40,000grams.

The protein extrudates may exhibit a wide range of particle sizes andmay generally be characterized as an oval or round nugget or pellet. Thefollowing weight percents for characterizing the particle sizes of theextrudates of the present invention are provided on an “as is” (i.e.,moisture-containing) basis.

In certain embodiments, the particle size of the extrudate is such thatfrom about 5% to about 10% by weight of the particles are retained on a6 Mesh Standard U.S. sieve, from about 80% to about 90% by weight of theparticles are retained on an 8 Mesh Standard U.S. sieve, from about 5%to about 10% by weight are retained on a 10 Mesh Standard U.S. sieve,and from about 1% to about 3% by weight of the particles pass through a10 Mesh Standard U.S. Sieve.

Such extrudates typically have a length of from about 3 to about 7 mmand, more typically, about 5 mm. The width of such extrudates istypically from about 0.5 to about 3.5 mm and, more typically, about 2mm.

Extrudates having such particle sizes are shown in the photomicrographsin FIGS. 2 and 3.

Extrudate nuggets having these characteristics may be shredded toproduce a textured soy protein product such that from about 5% to about10% by weight of the particles are retained on a 1/8 inch Standard U.S.sieve, from about 10% to about 20% by weight (typically about 15% byweight) of the particles are retained on a 6 Mesh Standard U.S. Sieve,from about 60% to about 80% by weight (typically 70% by weight) of theparticles are retained on a 20 Mesh Standard U.S. Sieve, and from about3% to about 5% by weight of the particles pass through a 20 MeshStandard U.S. Sieve. Such shredded extrudates are shown in FIG. 4.

In other embodiments, the particle size of the extrudate is such thatfrom 5% to about 10% by weight are retained on a 4 Mesh Standard U.S.sieve, from about 60% to about 80% by weight are retained on a 6 MeshStandard U.S. sieve, from about 20% to about 40% by weight are retainedon an 8 Mesh Standard U.S. sieve, and from about 1% to about 3% byweight of the particles pass through a 8 Mesh Standard U.S. Sieve.

Such extrudates typically have a length of from about 6 to about 10 mmand, more typically, about 8 mm. The width of such extrudates istypically from about 2.5 to about 5.5 mm and, more typically, about 4mm.

Extrudates having such particle sizes are shown in the photomicrographsin FIGS. 2, 3, and 5.

Extrudate nuggets having these characteristics may be shredded toproduce a textured soy protein product having a particle size such thatfrom about 10% to about 20% by weight are retained on a 1/4 inchStandard U.S. sieve, from about 50% to about 80% by weight (typicallyabout 65% by weight) are retained on a 7 Mesh Standard U.S. sieve, fromabout 20% to about 50% by weight (typically about 35% by weight) areretained on a 16 Mesh Standard U.S. Sieve, and from about 3% to about 5%by weight pass through a 16 Mesh Standard U.S. sieve. Such shreddedextrudates are shown in FIG. 4.

In still other embodiments, the particle size of the extrudate is suchthat from 5% to about 10% by weight of the particles are retained on a1/2 inch Standard U.S. sieve, from about 80% to about 90% by weight ofthe particles are retained on a 1/4 inch Standard U.S. sieve, and fromabout 1% to about 3% by weight pass through a 1/4 inch Standard U.S.Sieve.

Such extrudates typically have a length of from about 7 to about 13 mmand, more typically, about 10 mm. The width of such extrudates istypically from about 4 to about 10 mm and, more typically, about 7.5 mm.Extrudates having such particle sizes are shown in FIG. 2.

The extrudate nuggets described above may be ground to produce apowdered soy protein product. Such powder typically exhibits a particlesize such that from about 2% to about 5% by weight of the powder isretained on a 200 Mesh Standard U.S. Sieve, from about 10% to about 25%by weight of the powder is retained on a 325 Mesh Standard U.S. Sieve,and from about 70% to about 100% by weight (typically about 75% byweight) of the powder passes through a 325 Mesh Standard U.S. Sieve.Ground extrudates are shown in FIG. 4.

The products can also have a wide range of pellet durability index (PDI)values usually on the order of from about 65-99, more preferably fromabout 80-97.

The extrudates of the present invention are suitable for incorporationinto a variety of food products including, for example, food bars andready to eat cereals. Such extrudates may generally be oval or round andmay be also be shredded.

In certain embodiments, the protein extrudate is ground or comminuted asdescribed above to produce a powdered extrudate. Typically, such powderhas an average particle size of less than about 10 μm. More typically,the average particle size of the comminuted extrudate is less than about5 μm and, still more typically, from about 1 to about 3 μm. Suchpowdered extrudates are suitable for incorporation into a variety offood products including, for example, beverages, dairy products (e.g.,soy milk and yogurt), baked products, meat products, soups, and gravies.The protein extrudates can be incorporated in such applications in theform of nuggets or pellets, shredded nuggets or pellets, or powders asdescribed above.

Experience to date suggests that a particle size of less than about 5 μmis particularly desirable in the case of extrudates incorporated intobeverages to prevent a “gritty” taste in the product.

A particularly preferred application in which the soy protein product ofthe present invention is used is in emulsified meats. The soy proteinproduct may be used in emulsified meats to provide structure to theemulsified meat, which gives the emulsified meat a firm bite and a meatytexture. The soy protein product also decreases cooking loss of moisturefrom the emulsified meat by readily absorbing water, and prevents“fatting out” of the fat in the meat so the cooked meat is juicier.

The meat material used to form a meat emulsion in combination with thesoy protein product of the present invention is preferably a meat usefulfor forming sausages, frankfurters, or other meat products which areformed by filling a casing with a meat material, or can be a meat whichis useful in ground meat applications such as hamburgers, meat loaf andminced meat products. Particularly preferred meat material used incombination with the soy protein product includes mechanically debonedmeat from chicken, beef, and pork; pork trimmings; beef trimmings; andpork backfat.

A meat emulsion containing a meat material and the ground soy proteinproduct contains quantities of each which are selected to provide themeat emulsion with desirable meat-like characteristics, especially afirm texture and a firm bite.

Typically, the ground soy protein product is present in the meatemulsion in an amount of from about 0% to about 4% by weight, moretypically from about 0% to about 3% by weight and, still more typically,from about 1% to about 3% by weight.

Typically, the meat material is present in the meat emulsion in anamount of from about 40% to about 95% by weight, more typically fromabout 50% to about 90% by weight and, still more typically, from about60% to about 85% by weight.

The meat emulsion also contains water, which is typically present in anamount of from about 0% to about 25% by weight, more typically fromabout 0% to about 20% by weight, even more typically from about 0% toabout 15% by weight and, still more typically, from about 0% to about10% by weight.

The meat emulsion may also contain other ingredients that providepreservative, flavoring, or coloration qualities to the meat emulsion.For example, the meat emulsion may contain salt, typically from about 1%to about 4% by weight; spices, typically from about 0.1% to about 3% byweight; and preservatives such as nitrates, typically from about 0.001%to about 0.5% by weight.

The soy protein product of the present invention may also be used inbeverage applications including, for example, acidic beverages.Typically, the ground soy protein product is present in the beverage inan amount of from about 0.5% to about 3.5% by weight. The beverages inwhich the soy protein product is incorporated typically contain fromabout 70% to about 90% by weight water. The beverages typically alsocontain sugars (e.g., fructose and sucrose) in an amount of up to about20% by weight.

Preferred food product formulations are described below in variousformulation examples.

In the case of product for the healthy diet consumer, the dried formedproduct has total protein (e.g., hydrolyzed and unhydrolyzed) in therange of between about 25% and 55%, by weight of dried formed product.The ratio of at least partially hydrolyzed soy isolates to unhydrolyzedor gelling protein is in the range of between about 80:20 to about 55:45preferably in the range of between about 60:20 to about 60:45 and mostpreferably about 60:40. Filler, preferably a carbohydrate such as starch(a complex carbohydrate), is present in the range of between about 50%and 75% by weight of dried formed product. The total moisture content ispresent as described above coating can be applied to the dried formedproduct as described above. Also, the above-mentioned optionalingredients can also be added, for example, nutrients, flavorants,anti-microbial agents, etc. The total fat content of the finishedproduct, i.e., the dried formed product with flavoring and additivesadded thereto is less than about 5% and preferably in the range ofbetween about 0.2% and about 5% by weight of finished product.

In the case of product for the balanced diet consumer, protein ispresent in the range of between about 55% and 70% by weight of driedformed product. The ratio of at least partially hydrolyzed soy isolatesto the unhydrolyzed or gelling protein is in the range of between about80:20 to about 55:45 and preferably about 70:30. Filler, preferablystarch, is present in the range of between about 30% and 50% by weightof dried formed product. Typically, balanced diet consumers prefer ahigher fat content since they view fat as an important element of abalanced diet. In this event, total fat in the finished product is inthe range of between about 0.2% and about 20%, and preferably in therange of between about 15% and about 20% by weight of finished product.Most of the fat is preferably added with the coating since it isdesirable to not mix the fat prior to extrusion in with the componentsof the product that are extruded. The other ingredients as mentioned forthe healthy diet consumer can also be added to this product category inapproximately the same amounts.

For the high protein diet consumer product, it is preferred to addlittle if any filler in order to increase the protein content and reducethe carbohydrate content which to some consumers is detrimental to ahigh protein diet. For such a product line, the protein is present inthe range of between about 70% and 95% by weight of dried formedproduct. The ratio of at least partially hydrolyzed soy isolates tounhydrolyzed or gelling protein is in the range of between about 80:20and about 55:45 and preferably about 70:30. Filler, is kept low and ispresent in the range of between about 0% and about 30%, preferably inthe range of between about 5% and about 20% by weight of dried formedproduct. Fat, can be present in this type of product and wouldpreferably be added with the coating. Fat is present in the range ofbetween about 0.2% and about 30% and preferably in the range of betweenabout 7% and about 20% by weight of finished product. Other optionalingredients as discussed above can be added to this type of product inapproximately the same amounts.

EXAMPLES

The following examples are simply intended to further illustrate andexplain the present invention. The invention, therefore, should not belimited to any of the details in these examples.

Example 1

This example illustrates the preparation of soy protein nuggetscomprising 70%, 75%, 80%, 85%, and 88% soy protein using various feedmixture formulations.

The feed mixtures are described below in Table 3. TABLE 3 Product 75%80% 85% 88% Feed composition 70% protein protein protein protein proteinSUPRO 670 63.6% 68.2% 71.7%  77.3% 100%  SUPRO 620 15.9% 17.0% 17.8% 19.3% 0% Tapioca starch 18.2% 12.5% 9.0%  3.4% 0% Fibrim   2%   2% 1.2%  0% 0% NaCl  0.3%  0.3% 0.3%   0% 0%

As shown in Table 3, the weight ratio of hydrolyzed to unhydrolyzedisolates is approximately 4:1 in the feed mixtures for preparing the70%, 75%, 80%, and 85% protein nuggets. The 88% protein nuggets areprepared from a feed mixture which did not contain an unhydrolyzedisolate.

The ingredients of each feed mixture are mixed in an ingredient blenderfor 5 to 10 minutes to ensure uniform distribution. The dry feed mixtureis pneumatically conveyed to a volumetric feeder (i.e., hopper) and fedto a pre-conditioning tank at a rate of 6.3 to 7.7 kg/min (14-17 lb/min)in which the dry mix is pre-conditioned with steam and water. Water isintroduced to the pre-conditioner at a rate of 0.2 to 0.7 kg/min(0.5-1.5 lb/min) and steam is injected into a conditioning tank at arate of 0.16 to 0.22 kg/min (0.4-0.5 lb/min or 25-30 lb/hr). The mixturein the pre-conditioner is continuously stirred with a paddle rotating at1300-1500 rpm and the flow of steam is carefully monitored to maintainthe temperature of the protein mixture within the pre-conditionerbetween about 60° and about 70.5° C. (140° F.-159° F.).

The dry mix is then introduced to the inlet of the extruder barrel inletby a conveyor. Conditioned feed mix is introduced into the extruder at arate of 6 to 9 kg/min (13.3 to 20 lb/min) using an extruder screw speedof from 275 to 320 rpm.

The extruder used is a double-barrel, twin-screw extruder, CLEXTRALModel BC-72 manufactured by Clextral, Inc. (Tampa, Fla.) having an L/Dratio of 15:1 and four heating zones. The screw profile for the extruderis described in Table 4. TABLE 4 Length Pitch 200 100  200 100  150 100 200 66 200 66 100 50 100 40 100  30**Reverse

Water is introduced into the extruder barrel at a rate of 1.8 to 2.7kg/min (4-6 lb/min) without steam injection. The barrel temperatures arecontrolled with a Mokon temperature control system manufactured byClextral (Tampa, Fla.). The extruder contains 4 heating zones throughwhich the feed mixture passes, the temperature profile of the BC-72extruder is shown in Table 5 below. TABLE 5 Extrusion ExtrusionExtrusion Extrusion Zone 4 Pre-conditioner Zone 1 Zone 2 Zone 3 (Dieend) 60-71° C. 28-29.5° C. 93-96° C. 132-135° C. 140-146° C. (140-160°F.) (82-85.1° F.) (200-205° F.) (270-275° F.) (284-295° F.)

The conditioned feed mix is cooked in the extruder barrel withmechanical energy generated from the extruder screw rpm/shear andelectrical energy at high temperatures to reach the glass transitiontemperature. At high temperatures, shear, and pressure the feed mixmelts and interacts with water and other ingredients to form a plasticlike material which is then extruded through backup plate having a≦1-inch (25-mm) diameter before passing through an extrusion die.

The extrudates are cut using a 6 bladed knife rotating at 2000-3000 rpmto obtain the product size, density and granulation. The die knife areais ventilated by sparging compressed air (within the cutter guard) toaid face plate cooling/product cutting.

The soy protein nuggets are dried with a Proctor single band conveyordryer at a temperature of from about 145° to about 165° C. (295° toabout 325° F.) for a residence time of 5-7 minutes. The dried soynuggets are sieved using #3 and #8 Sweco sieves to remove the fines.

The hardness of the extrudates is determined using a texture analyzer,Model # TA.TXT2 with a 25 kg load cell manufactured by Stable MicroSystems Ltd. (England). The density and hardness of the various soyprotein extrudates are summarized below in Table 6. TABLE 6 Proteincontent (%) Density (g/cm³) Texture (g) 70 0.235 21680.1 75 0.24723918.7 80 0.256 25230.2 85 0.234 22526.4

The effect of varying certain process conditions for various runs usedto prepare 80% soy protein nuggets are summarized below in Table 7.TABLE 7 Effect of Extruder Screw Speed, Water Feed Rate, and MixtureFeed Rate on Power Required and Density and Texture of 80% Soy ProteinNuggets Barrel Water Mixture Power Extruder Feed Rate Feed requiredDensity Texture Run RPM (%) (%) Rate (%) (AMPS) (g/cc) (g) 1 90 80 85 800.122 5535.4 2 80 90 85 104 0.2436 25850.6 3 90 90 85 104 0.2216 16706.64 90 90 85 104 0.2278 18138.3 5 80 80 75 80 0.2518 23821.3 6 90 90 75 800.2163 14992.1 7 85 85 80 104 0.237 19387.5 8 80 90 75 80 0.2458 21717.79 90 80 75 85 0.2091 13092.1 10 80 80 85 90 0.2518 24777.1 11 85 85 80104 0.2328 19065.7 12 90 80 75 80 0.2161 12855.7 13 90 80 85 90 0.13316234.8 14 80 80 85 80 0.2444 23395.8 15 90 90 75 80 0.2161 12322.4 16 8090 75 90 0.2728 29065.4 17 80 90 85 85 0.2583 26035.7 18 80 80 75 900.2466 24827The equivalents of extruder rpm (%), mixture feed rate (%) and extruderbarrel water rate (%) are presented below:Extruder rpm:

-   80%=267 rpm-   85%=284 rpm-   90%=301 rpm    Extruder feed rate:-   75%=15 lb/min-   80%=16 lb/min-   85%=17 lb/min    Extruder barrel water rate:-   80%=4.8 lb/min-   85%=5.1 lb/min-   90%=5.4 lb/min

Preferred formulations are provided in the following formulationexamples. All percents (%) are by weight. Nutritional Bar (sheet and cuttype) Ingredients % Marshmallow mixture 39.0 sugar polydextrose cornsyrup margarine water corn syrup High soy protein nuggets 31.5 DriedApples 13.5 Dried cranberries 13.0 Soybean oil 2.0 Cranberry juiceconcentrate 1.0 Total 100 Nutritional Bar (extruded) Ingredients %Ground, Comminuted high soy 34.2 protein nuggets Corn syrup 26.0 HighFructose corn syrup 21.3 Rice Syrup solids, 26 DE 7.85 Glycerin 3.95Vitamin and mineral premix 0.70 Natural and artificial 0.67 flavors(Chocolate & Vanilla) Salt 0.11 Total 100.00 Acidic pH beverageIngredients % Water 84.59 Sucrose 4.29 Ground, Comminuted high soy 1.65protein nuggets Fructose 2.91 Carrot concentrate, 42 Brix 4.02 Citricacid 0.10 Pectin 0.45 Vitamin Premix 1.09 Phosphoric acid (75%) 0.7Natural and Artificial Flavor 0.2 Total 100.00 Emulsified meat systemIngredient % Beef Trim (10% Fat) 33.4 Pork Trim (27% Fat) 2.8 Pork Trim(57% Fat) 25.1 Ground, Comminuted high soy 2.0 protein nuggets Spices0.53 Sodium phosphate 0.4 Sodium nitrite 0.01 Sodium Erythorbate 0.02Dextrose 1.0 Corn Syrup Solids 2.0 Oleoresin Blend 0.01 Garlic Powder0.01 Onion Powder 0.02 Total 100.0 Ground meat, beef patties Ingredient% Beef Trim (10% Fat) 59.00 Beef Trim (15% Fat) 10.00 Beef Trim (50%Fat) 25.00 Water 5.0 Ground, Comminuted high soy 1.0 protein nuggetsTotal 100.00 High protein cookie Ingredients % Butter 11.00 Butterflavored shortening 8.00 Brown Sugar 7.50 Polydextrose 11.00 Invertsugar syrup 3.50 Whole eggs 10.50 Soy Lecithin 0.02 Vanilla 0.25 Cakeflour 5.30 Sodium bicarbonate 0.50 High soy protein nuggets 5.30 Ground,Comminuted high soy 10.50 protein nuggets Salt 0.25 Oats 15.43 Total100.00 Hot Dog Ingredients % Turkey (Mechanically deboned) 60.00 Beeftrimmings 15.00 Water 15.00 Salt 2.00 Curing salt (6.25% NaNO₂) 0.15Sodium ascorbate 0.05 Phosphate 0.30 Corn syrup solids 1.20 Groundtextured Soy protein 1.20 product Modified potato starch 1.20 Tomatopaste 2.00 Chili powder 0.50 Paprika powder 0.50 Cumin powder 0.25Dehydrated onions 0.25 Smoke flavor 0.10 Total 100.00 Smoked ItalianSausage Ingredients % Pork trimmings 49.20 Chicken (Mechanicallydeboned) 15.00 Pork fat trimmings 10.00 Water 20.00 Salt 1.70 Curingsalt (6.25% NaNO₂) 0.20 Phosphate 0.30 Sodium ascorbate 0.05 Groundtextured soy protein 1.60 product Non fat dry milk 0.80 Smoke flavor0.25 Paprika powder 0.25 Fennel 0.25 Red pepper 0.15 White pepper 0.15Anise 0.10 Total 100.00 Smoked Sausage Ingredients % Pork picnics 48.00Beef meat 20.00 Turkey (Mechanically deboned) 10.00 Water 15.00 Salt1.80 Curing salt 0.20 Sodium ascorbate 0.05 Corn syrup solids 1.50Ground textured soy protein 1.50 product Non fat dry milk 1.50 Whitepepper 0.25 Marjoram 0.10 Nutmeg 0.10 Total 100.00 Beef Smoked SausageIngredients % Beef meat 20.00 Beef navels 52.00 Water 20.00 Salt 2.10Curing salt (6.25% NaNO₂) 0.15 Sodium ascorbate 0.05 Corn syrup 2.20Ground textured Soy protein 2.20 product Non fat dry milk powder 0.60Onion powder 0.20 Seasoning 0.50 Total 100.00 Variety Meat SmokedSausage Ingredients % Beef tripe (flaked/ground) 16.00 Beef head meat(flaked/ground) 10.00 Beef meat (pre-cured) 10.00 Beef heart emulsion10.00 Beef tongue 16.00 Pork meat (pre-cured) 10.00 Chicken(Mechanically deboned) 10.00 Water 10.00 Salt 2.30 Curing salt (6.25%NaNO₂) 0.15 Sodium ascorbate² 0.05 Corn syrup 2.30 Ground textured Soyprotein 2.30 product Seasoning 0.90 Total 100.00

The present invention is not limited to the above embodiments and can bevariously modified. The above description of preferred embodiments isintended only to acquaint others skilled in the art with the invention,its principles and its practical application so that others skilled inthe art may adapt and apply the invention in its numerous forms, as maybe best suited to the requirements of a particular use.

With reference to the use of the word(s) “comprise” or “comprises” or“comprising” in this entire specification (including the claims below),it is noted that unless the context requires otherwise, those words areused on the basis and clear understanding that they are to beinterpreted inclusively, rather than exclusively, and that it isintended each of those words to be so interpreted in construing thisentire specification.

1. A protein extrudate comprising at least about 70% by weight vegetableprotein on a moisture-free basis and having a density of from about 0.10g/cm³ to about 0.40 g/cm³.
 2. A protein extrudate as set forth in claim1 comprising at least about 70% by weight soy protein on a moisture-freebasis.
 3. A protein extrudate as set forth in claim 2 wherein saidextrudate comprises less than about 10% by weight carbohydrate on amoisture-free basis.
 4. A protein extrudate as set forth in claim 3wherein said extrudate comprises from about 2% to about 5% by weightcarbohydrate on a moisture-free basis.
 5. A protein extrudate as setforth in claim 3 wherein said extrudate comprises from about 2% to about5.5% by weight water on a total weight basis.
 6. A protein extrudate asset forth in claim 2 wherein said extrudate has a density of from about0.15 g/cm³ to about 0.35 g/cm³.
 7. A protein extrudate as set forth inclaim 6 wherein said extrudate has a density of from about 0.20 g/cm³ toabout 0.27 g/cm³.
 8. A protein extrudate as set forth in claim 7 whereinsaid extrudate has a density of from about 0.24 g/cm³ to about 0.27g/cm³.
 9. A protein extrudate as set forth in claim 6 wherein saidextrudate has a density of from about 0.27 g/cm³ to about 0.32 g/cm³.10. A protein extrudate as set forth in claim 2 comprising from about 2to about 8 parts by weight hydrolyzed soy protein per part by weightunhydrolyzed soy protein.
 11. A protein extrudate as set forth in claim10 wherein said hyrolyzed soy protein exhibits a degree of hydrolysis ofless than about 15%.
 12. A protein extrudate as set forth in claim 11wherein said hydrolyzed soy protein exhibits a degree of hydrolysis ofless than about 10%.
 13. A protein extrudate as set forth in claim 12wherein said hydrolyzed soy protein exhibits a degree of hydrolysis offrom about 1% to about 5%.
 14. A protein extrudate as set forth in claim10 wherein said hydrolyzed soy protein exhibits a TNBS value of fromabout 30 to about
 70. 15. A protein extrudate as set forth in claim 2comprising at least about 80% by weight soy protein on a moisture-freebasis.
 16. A protein extrudate as set forth in claim 15 wherein saidextrudate comprises less than about 10% by weight carbohydrate on amoisture-free basis.
 17. A protein extrudate as set forth in claim 16wherein said extrudate comprises from about 2% to about 5% by weightcarbohydrate on a moisture-free basis.
 18. A protein extrudate as setforth in claim 16 wherein said extrudate comprises from about 2% toabout 5.5% by weight water on a total weight basis.
 19. A proteinextrudate as set forth in claim 15 wherein said extrudate has a densityof from about 0.15 g/cm³ to about 0.35 g/cm³.
 20. A protein extrudate asset forth in claim 19 wherein said extrudate has a density of from about0.20 g/cm³ to about 0.27 g/cm³.
 21. A protein extrudate as set forth inclaim 20 wherein said extrudate has a density of from about 0.24 g/cm³to about 0.27 g/cm³.
 22. A protein extrudate as set forth in claim 19wherein said extrudate has a density of from about 0.27 g/cm³ to about0.32 g/cm³.
 23. A protein extrudate as set forth in claim 22 comprisingfrom about 2 to about 8 parts by weight hydrolyzed soy protein per partby weight unhydrolyzed soy protein.
 24. A protein extrudate as set forthin claim 23 wherein said hyrolyzed soy protein exhibits a degree ofhydrolysis of less than about 15%.
 25. A protein extrudate as set forthin claim 24 wherein said hydrolyzed soy protein exhibits a degree ofhydrolysis of less than about 10%.
 26. A protein extrudate as set forthin claim 25 wherein said hydrolyzed soy protein exhibits a degree ofhydrolysis of from about 1% to about 5%.
 27. A protein extrudate as setforth in claim 23 wherein said hydrolyzed soy protein exhibits a TNBSvalue of from about 30 to about
 70. 28. A protein extrudate as set forthin claim 2, wherein said extrudate comprises from about 80% to about 95%by weight soy protein on a moisture-free basis.
 29. A protein extrudateas set forth in claim 28 wherein said extrudate comprises less thanabout 5% by weight carbohydrate on a moisture-free basis.
 30. A proteinextrudate as set forth in claim 29 wherein said extrudate comprises fromabout 2% to about 5% by weight carbohydrate on a moisture-free basis.31. A protein extrudate as set forth in claim 28 wherein said extrudatecomprises from about 2% to about 5% by weight water on a total weightbasis.
 32. A protein extrudate as set forth in claim 28 wherein saidextrudate has a density of from about 0.15 g/cm³ to about 0.35 g/cm³.33. A protein extrudate as set forth in claim 32 wherein said extrudatehas a density of from about 0.20 g/cm³ to about 0.27 g/cm³.
 34. Aprotein extrudate as set forth in claim 33 wherein said extrudate has adensity of from about 0.24 g/cm³ to about 0.27 g/cm³.
 35. A proteinextrudate as set forth in claim 32 wherein said extrudate has a densityof from about 0.27 g/cm³ to about 0.32 g/cm³.
 36. A protein extrudate asset forth in claim 28 comprising from about 2 to about 8 parts by weighthydrolyzed soy protein per part by weight unhydrolyzed soy protein. 37.A protein extrudate as set forth in claim 2 wherein said extrudate has ahardness of at least about 10,000 grams, as measured by a textureanalyzer having a 25 kg load cell.
 38. A protein extrudate as set forthin claim 37 wherein said extrudate has a hardness of from about 1000grams to about 50,000 grams, as measured by a texture analyzer having a25 kg load cell.
 39. A protein extrudate as set forth in claim 38wherein said extrudate has a hardness of from about 30,000 grams toabout 45,000 grams, as measured by a texture analyzer having a 25 kgload cell.
 40. A protein extrudate as set forth in claim 2 wherein saidextrudate is in the form of a powder having an average particle size ofless than about 10 microns.
 41. A protein extrudate as set forth inclaim 40 wherein said powder has an average particle size of less thanabout 5 microns.
 42. A protein extrudate as set forth in claim 41wherein said extrudate comprises from about 0.001% to about 5% fiber ona moisture free basis.
 43. A protein extrudate as set forth in claim 42wherein said extrudate comprises from about 1% to about 3% by weightfiber on a moisture free basis.
 44. A protein extrudate comprisingunhydrolyzed vegetable protein and at least about 2 parts by weighthydrolyzed protein per part by weight unhydrolyzed protein.
 45. Aprotein extrudate as set forth in claim 44 comprising unhydrolyzed soyprotein and at least about 2 parts by weight hydrolyzed soy protein perpart by weight unhydrolyzed soy protein.
 46. A protein extrudate as setforth in claim 45 comprising from about 2 to about 8 parts by weighthydrolyzed soy protein per part by weight unhydrolyzed soy protein. 47.A protein extrudate as set forth in claim 46 comprising from about 4 toabout 6 parts by weight hydrolyzed soy protein per part by weightunhydrolyzed soy protein.
 48. A protein extrudate as set forth in claim46 herein said hyrolyzed soy protein exhibits a degree of hydrolysis ofless than about 15%.
 49. A protein extrudate as set forth in claim 48wherein said hydrolyzed soy protein exhibits a degree of hydrolysis ofless than about 10%.
 50. A protein extrudate as set forth in claim 49wherein said hydrolyzed soy protein exhibits a degree of hydrolysis offrom about 1% to about 5%.
 51. A protein extrudate as set forth in claim49 wherein said hydrolyzed soy protein exhibits a TNBS value of fromabout 30 to about
 70. 52. A protein extrudate as set forth in claim 49wherein said extrudate comprises at least about 70% by weight soyprotein.
 53. A protein extrudate as set forth in claim 52 wherein saidextrudate comprises less than about 10% by weight carbohydrate on amoisture-free basis.
 54. A protein extrudate as set forth in claim 53wherein said extrudate comprises from about 2% to about 5% by weightcarbohydrate on a moisture-free basis.
 55. A protein extrudate as setforth in claim 53 wherein said extrudate comprises from about 2% toabout 5.5% by weight water on a total weight basis.
 56. A proteinextrudate as set forth in claim 46 wherein said extrudate has a densityof from about 0.10 g/cm³ to about 0.40 g/cm³.
 57. A protein extrudate asset forth in claim 56 wherein said extrudate has a density of from about0.15 g/cm³ to about 0.35 g/cm³.
 58. A protein extrudate as set forth inclaim 57 wherein said extrudate has a density of from about 0.24 g/cm³to about 0.29 g/cm³.
 59. A protein extrudate as set forth in any claim56 wherein said extrudate has a density of from about 0.20 g/cm³ toabout 0.27 g/cm³.
 60. A protein extrudate as set forth in claim 46wherein said extrudate comprises at least about 80% by weight soyprotein.
 61. A protein extrudate as set forth in claim 60 wherein saidextrudate comprises less than about 10% by weight carbohydrate on amoisture-free basis.
 62. A protein extrudate as set forth in claim 61wherein said extrudate comprises from about 2% to about 5% by weightcarbohydrate on a moisture-free basis.
 63. A protein extrudate as setforth in claim 61 wherein said extrudate comprises from about 2% toabout 5.5% by weight water on a total weight basis.
 64. A proteinextrudate as set forth in claim 60 wherein said extrudate has a densityof from about 0.10 g/cm³ to about 0.40 g/cm³.
 65. A protein extrudate asset forth in claim 64 wherein said extrudate has a density of from about0.15 g/cm³ to about 0.35 g/cm³.
 66. A protein extrudate as set forth inclaim 65 wherein said extrudate has a density of from about 0.20 g/cm³to about 0.27 g/cm³.
 67. A protein extrudate as set forth in claim 60wherein said extrudate has a density of from about 0.24 g/cm³ to about0.27 g/cm³.
 68. A protein extrudate as set forth in claim 46 whereinsaid extrudate comprises from about 80% to about 95% by weight soyprotein.
 69. A protein extrudate as set forth in claim 68 wherein saidextrudate comprises less than about 5% by weight carbohydrate on amoisture-free basis.
 70. A protein extrudate as set forth in claim 69wherein said extrudate comprises from about 2% to about 5% by weightcarbohydrate on a moisture-free basis.
 71. A protein extrudate as setforth in claim 46 wherein said extrudate has a density of from about0.10 g/cm³ to about 0.40 g/cm³.
 72. A protein extrudate as set forth inclaim 71 wherein said extrudate has a density of from about 0.15 g/cm³to about 0.35 g/cm³.
 73. A protein extrudate as set forth in claim 72wherein said extrudate has a density of from about 0.20 g/cm³ to about0.27 g/cm³.
 74. A protein extrudate as set forth in claim 73 whereinsaid extrudate has a density of from about 0.24 g/cm³ to about 0.27g/cm³.
 75. A protein extrudate as set forth in claim 46 wherein saidextrudate has a hardness of from about 1000 grams to about 50,000 grams,as measured by a texture analyzer having a 25 kg load cell.
 76. Aprotein extrudate as set forth in claim 75 wherein said extrudate has ahardness of from about 30,000 grams to about 45,000 grams, as measuredby a texture analyzer having a 25 kg load cell.
 77. A protein extrudateas set forth in claim 46 wherein said extrudate is in the form of apowder having an average particle size of less than about 10 microns.78. A protein extrudate as set forth in claim 77 wherein said powder hasan average particle size of less than about 5 microns.
 79. A proteinextrudate as set forth in claim 78 wherein said extrudate comprises fromabout 0.001% to about 5% fiber on a moisture free basis.
 80. A proteinextrudate as set forth in claim 79 wherein said extrudate comprises fromabout 1% to about 3% by weight fiber on a moisture free basis.
 81. Afunctional food ingredient comprising from about 40% to about 95% byweight meat material and up to about 4% by weight of a soy proteinproduct on a total weight basis, the soy protein product comprising atleast about 70% by weight soy protein on a moisture-free basis andhaving a density of from about 0.10 g/cm³ to about 0.40 g/cm³.
 82. Afunctional food ingredient as set forth in claim 81 wherein said meatmaterial is present at a concentration of from about 50% to about 90% byweight.
 83. A functional food ingredient as set forth in claim 81wherein said meat material is present at a concentration of from about60% to about 85% by weight.
 84. A functional food ingredient as setforth in claim 81 wherein said soy protein product is present at aconcentration of up to about 3% by weight.
 85. A functional foodingredient as set forth in claim 81 wherein said soy protein product ispresent at a concentration of from about 1% to about 3% by weight.
 86. Alow density snack food product including a majority solids component anda water component with the majority solids component including at leastprotein, said food product comprising: protein in the range of betweenabout 25% and about 95% by weight of majority solids component andwater, said protein being derived from seed crops selected from thegroups of cereal grains and legumes; water in the range of between about1% and about 7% by weight of solids and water; and said product beingcharacterized by having a crisp texture, a density in the range ofbetween about 0.02 g/cm³ and about 0.5 g/cm³ based on the weight ofsolids component and water.
 87. A food product as set forth in claim 86wherein said product is further characterized by having a non-fibrouseating texture.
 88. A food product as set forth in claim 86 wherein themajority solids component includes filler present in a ratio of fillerto protein in the range of between about 5:95 and about 75:25.
 89. Afood product as set forth in claim 88 wherein the protein includes amajority of soy protein.
 90. A food product as set forth in claim 89wherein the soy protein includes at least partially hydrolyzed soyprotein and unhydrolyzed soy protein.
 91. A food product as set forth inclaim 90 wherein the at least partially hydrolyzed soy protein includesat least partially hydrolyzed soy isolates and the unhydrolyzed soyprotein includes at least one of soy isolates, soy concentrates and soyflour wherein the at least partially hydrolyzed soy protein is presentin the ratio of between about 80:20 and about 55:45 to the unhydrolyzedsoy protein.
 92. A food product as set forth in claim 91 wherein atleast a majority of the filler is starch.
 93. A food product as setforth in claim 92 wherein the starch is present in a ratio to protein inthe range of between about 5:95% and about 75:25% by weight of protein,filler and water.
 94. A food product as set forth in claim 93 whereinthe density of the food product is in the range of between about 0.02g/cm³ and about 0.1 g/cm³.
 95. A food product as set forth in claim 94wherein the density of the food product is in the range of between about0.02 g/cm³ and about 0.05 g/cm³.
 96. A food product as set forth inclaim 94 wherein the moisture content of the food product is in therange of between about 3% and about 5% by weight of protein, filler andwater.
 97. A low density, low moisture content proteinaceous foodproduct comprising a principal solid component and containing betweenabout 1% and about 7% water, said principal solid component comprisingprotein in a concentration between about 25% and about 95% by weight ofthe sum of the water content of said product and the dry basis weight ofsaid principal solid component, said product being characterized by acrisp texture and a density in the range between about 0.02 g/cm³ andabout 0.5 g/cm³ based on the weight of said principal solid componentand water.
 98. A food product as set forth in claim 97 wherein saidprincipal solid component further comprises a filler in a weight ratioto protein between about 5:95 and about 75:25.
 99. A food product as setforth in claim 98 wherein more than half the protein content consists ofsoy protein.
 100. A food product as set forth in claim 99 wherein thesoy protein includes at least partially hydrolyzed soy protein andunhydrolyzed soy protein.
 101. A low density, low moisture contentproteinaceous food product comprising a proteinaceous solid matrix andcontaining between about 1% and about 7% water, said matrix comprisingprotein in a concentration between about 25% and about 95% by weight ofthe sum of the water content of said product and the dry basis weight ofsaid matrix, said product being characterized by a crisp texture, adensity in the range between about 0.02 g/cm³ and about 0.5 g/cm³. 102.A food product as set forth in claim 101 wherein said matrix furthercomprises a filler in a weight ratio to protein between about 5:95 andabout 75:25.
 103. A food product as set forth in claim 102 wherein morethan half the protein content consists of soy protein.
 104. A foodproduct as set forth in claim 103 wherein the soy protein includes atleast partially hydrolyzed soy protein and unhydrolyzed soy protein.105. A low density, low moisture content proteinaceous food productcomprising a proteinaceous solid extrudate and containing between about1% and about 7% water, said extrudate comprising protein in aconcentration between about 25% and about 95% by weight of the sum ofthe water content of said product and the dry basis weight of saidextrudate, said product being characterized by a crisp texture, adensity in the range between about 0.02 g/cm³ and about 0.5 g/cm³. 106.A food product as set forth in claim 105 wherein said extrudate furthercomprises a filler in a weight ratio to protein between about 5:95 andabout 75:25.
 107. A food product as set forth in claim 106 wherein morethan half the protein content consists of soy protein.
 108. A foodproduct as set forth in claim 107 wherein the soy protein includes atleast partially hydrolyzed soy protein and unhydrolyzed soy protein.109. A low density, low moisture content proteinaceous food productcomprising between about 1% and about 7% water and between about 25% andabout 95% by weight of protein, wet basis, said product beingcharacterized by a crisp texture, a density in the range between about0.02 g/cm³ and about 0.5 g/cm³.